Helicopter saws next to power lines

Finland, like other countries, has a high-voltage grid with pylons and cables. To a large extent, these cables go right through forests. This means that regular checks must be made to ensure that the cables are not still bothered by growing trees. Much is done from the ground, but an important part is maintained by a ‘saw helicopter’.

In summer 2021, a helicopter flew an impressive-looking sawmill in the forests near Lake Saima. This was a measure to increase the distribution security of the power grid, i.e. the saws cut branches that reached up to the high-voltage pylons and cables.

The sides of the stretches where the high-voltage pylons are located are ‘cleaned’ by helicopter annually up to a distance of 500 km. Foresters, on the other hand, inspect more than 1,000 km of sections near the pylons every year and clean them if necessary.

This time, sections requiring a helicopter saw were found in Anttola, Savonlinna and Kangasniemi, among others. After cutting, the branches of coniferous trees do not grow, but deciduous trees can cause problems by bending over the power lines or growing new branches.

Clean-up by helicopter is a challenging task

Helicopter centre pilot Marko Patovisti has been cleaning key routes for decades and is one of Finland’s most experienced helicopter pilots. He has more than 10,000 hours of experience at the controls of a helicopter.

“I was not afraid to start this job without experience. I already had lifting experience with a helicopter and that helped to get started with sawing. Helicopter sawing is one of the most challenging tasks you do with a helicopter” notes Marko.

The sawing device used to saw was designed and built in-house. Eight blades of almost half a metre are mounted on the frame beam and this is attached to the motor housing, which spins at a tremendous speed. The saw is attached to the end of the boom, which swings back and forth as the helicopter flies. There is always another helicopter professional involved, who takes care of refuelling, maintenance of the helicopter and the saws.

Helicopter saw safety is ensured in many ways

Helicopter sawing is always done safely and without risk. If the weather is bad, the helicopter stays on the ground. Work is done carefully and with enough time. Unnecessary haste can lead to unnecessary power cuts or accidents.

“Sawing is done with due care and patience. You could work faster, but as the speed increases, more loose branches will fly around. If they hit the power lines, they can interrupt the electricity supply” says Marko.

Occasionally, branches that have been cut away still fall on the cables, interrupting electricity. These are removed by the power grid maintenance company in the region. This has the means to remove the branches from the high-voltage power lines.

source: Järvi-Suomen Energia